Yieldable wall assembly for containers for the transportation of low-temperature fluids



April 14, 1970 R. VQN4S'ALDERN YIELDABLE WALL ASSEMBLY FOR CONTAINERS FOR THE TRANSPORTATION OF LOW-TEMPERATURE FLUIDS 2 Sheets-Sheet 1 Filed May 14. 1968 FIG.I

F l G 3 I INVENTOR, RUDIGER Von SALDERN {Karl 9'. IR:

ATTOR NEY Apnl 14. 1970 R. VON SALDERN YIELDABLE WALL ASSEMBLY FOR CONTAINERS FOR THE TRANSPORTATION OF LOW-TEMPERATURE FLUIDS 2 Sheets-Sheet, '2

Filed May 14. 1968 F I6. I- B INVENTOR.

RUDIGER v0 SALDERN ATTORNEY United States Patent US. Cl. 29183.5 6 Claims ABSTRACT OF THE DISCLOSURE A yieldable wall assembly adapted to be mounted via load-supporting insulation and thermally insulating bolt constructions upon the rigid wall of a tankship or the like in which the wall is formed by laterally and longitudinally contiguous coplanar sheet-metal plates having upwardly turned flanges welded together to form flange seams provided at the junction of mutual orthogonal flange seams with gussets whereby the corners of the plates are welded together. The gussets are formed by bending the flanges of the plates alternately inwardly and outwardly of that weld-seam plane which is perpendicular to the plane of the yieldable wall.

My present invention relates to a container for the transportation of low-temperature fluids and, more particularly, to a tank or compartment in a seagoing vessel for the transportation of liquefied gases (e.g. methane) at low temperatures.

It has already been proposed to provide tankships for the transportation of liquefied gases (e.g. liquid hydrocarbons such as methane, ethane or propane, or air-rectification products such as nitrogen or ammonium) with rigid hulls forming holds containing a plurality of tanks thermally insulated from the hull and having fluidcontaining compartments which may be separated from the rigid wall by a continuous sheet-metal skin. The skin, which may flex in response to temperature fluctuations is composed of plates welded together in fluid tight relationship along their peripheries at upstanding flanges so that the welded peripheries of the trays or plates form expansion joints or folds accommodating thermal expansion and contraction of the skin. Between the sheet-metal skin and the hull of the ship, there is provided a filling of one or more layers of thermal insulation preferably of load-supporting or relatively incompressible character. In addition, the system of the latter application provides parallel arrays of shear-rail assemblies supporting the tank in load-transmitting relationship with the hull while thermally insulating the tank therefrom.

Insulating bolt assemblies attach the sheet-metal outer wall of a double-wall container to the hull of the ship via an intervening layer of load-supporting thermal insulation. A further layer of insulation, preferably of the nonsupporting type, may be interposed between the inner wall of the vessel and the intermediate sheet-metal layer. The bolt assembly comprises a bolt head welded sealingly to the sheet-metal layer and having a shank threaded into a cylindrical post of thermally insulating material, the post being threadedly anchored in a sleeve upstanding from and welded to the rigid wall of the vessel.

In such arrangements using an intermediate skin adapted to yield with temperature variations, elasticity is gained and stress is reduced by providing the sheetmetal wall of a plurality of plates in contiguous relationship, the plates having upturned flanges at the periph- "ice eries which are welded together at the corners of the plate to form individual pans or trays therefrom. The flanges of adjacent trays, which diverge upwardly are welded together at outwardly turned lips to form a continuous partition or wall precluding passage of fluid therepast. The flanges, when welded together, form folds in the continuous wall which, like accordion pleats, permit expansion and contraction of the sheets or trays in the plane thereof in response to the high-temperature fluctuations sustained by the walls upon filling of the tank with a low-temperature fluid or upon discharging the cargo.

Additional stress reduction is provided by offsetting the junctions between the plates, from plate to plate, along the continuous skin. This is accomplished by imparting to the plates a geometric configuration which corresponds substantially to a double trapezoid joint at the corresponding small base. More specifically, the plates are provided with a pair of parallel end edges and a pair of inwardly directed lateral edges and are joined together in laterally overlapping relationship so that the junction between a pair of ends of end-aligned plates is located substantially intermediate the ends of the neighboring side-aligned plates. Thus, the plates are connected end-to-end in adjacent rows which are oflset substantially by about half the length of the plates and each plate is widest at its end and narrowest at an intermediate region corresponding to the location of closest approach of the inwardly turned lateral sides. Preferably, this intermediate location lies at the center of the plate. A single bolt assembly secures the plate to the rigid Wall at the center of each plate.

In the flexible sheet-metal skin arrangement of the character described, problems may remain with respect to the corner junctions of the several plates. Thus, it appears that arrangements in which the flanges, upon welding together, form relative rigid nets, restrict expansion and contraction in both mutually perpendicular directions in the plane of this wall with particular stressing at the corners. Furthermore, this phenomenon is all the more significant when the trays are generally rectangular.

An object of the present invention is, therefore, to provide a corner junction for the plates of the yieldable wall assembly (e.g. as described and claimed in the aforementioned copending applications) which reduces the stress applied to the wall upon yielding.

I have now found that it is possible to decrease the stresses arising from the net-like arrangement of the seams between the plates or trays continuously connected into a thermally expandable and contractable wall assembly of the character described when, at each intersection point of the orthogonal welded flanged seams, a corner junction is provided which includes one or more gussets provided in the seam of at least one of the pairs of plates and welded to the corner-junction portions of the others. The gusset is formed by outwardly bending the flange of one plate and inwardly bending the corresponding portion of the flange of a contiguously adjoining plate. The intersection of orthogonal seams is constituted, according to this invention, by providing a plurality of lateral and longitudinally contiguous, generally coplanar, plates or trays whose upturned flanges are welded together with or without mutually confronting lips as described in th last-mentioned applications, for example, whereby the seams of four such plates constitute a corner junction. The present invention provides that each seam (consisting of two upturned parallel and converging flanges welded together along a seam line defining the edges of the plates) is provided at its ends with a gusset formed by bending the adjoining seam flanges in opposite directions (i.e. inwardly and outwardly) so that, with respect to a perpendicular plane through that scam, the weld at the inner and outer bends runs away from and toward this plane.

The term perpendicular plane is here used to describe the plane through the weld seam perpendicular to the plate and, therefore, the plane toward which the seam flanges converge upwardly. Each junction point is provided at the intersection of two such planes which are mutually perpendicular. Consequently, when the yieldable wall forms a horizontal floor, the intersecting perpendicular planes are vertical and, when the yieldable wall is vertical, one of the intersecting perpendicular planes is generally horizontal while the other is vertical. Preferably, the junction is constituted at the corners of four plates longitudinally contiguous in pairs, with the pairs being laterally contiguous so that the mutually perpendicular planes pass through the laterally seamed edges and the longitudinal end edges of the plate.

The gussets may be angular (formed as trapezoidal or triangular prisms) or arcuate (e.g. petal-shaped), provided only that the gussets are formed by portions extending first toward one side of the respective perpendicular planes and thence back to the latter. The gussets all should terminate, according to this invention, at a common point at the intersection of the orthogonal perpendicular planes and in the respective perpendicular plane at least when the apex of the seamed flange is considered. Each of the seamed flanges is thus of triangular crosssection and may be integral (i.e. one piece) with the gusset whereby only the weld seam is fully bent out of the respective perpendicular plane and thus back toward the latter. As a consequence, the gusset, in the direction of the point or line junction of the four-plate corners, has an outwardly turned fold and an inner fold. When the junction of the four-seamed flanges is considered, therefore, the flanged seams are respectively bent inwardly and outwardly such that the upper edge of an outer fold of the edge of one of the plates of a contiguous pair abuts and is welded to an inner fold of the neighboring edge of the other laterally or longitudinally contiguous plate. The gusse s at opposite ends of the seamed flange of any pair of plates are oriented in opposite senses and thus are of reciprocal symmetry.

The elastic regions of the weld seams are thus disposed in proximity to one another and a sharp increase in the elasticity of the entire assembly, especially at the corner junctions, is obtained. It has also been found to be advantageous that the seamed flanges be turned at somewhat less than 90 upwardly. The petal-shaped gussets at the corner junctions and the prismatic junctions of longitudinally aligned seams may have upper weld seams which are aligned with one another to form a continous, although bent, line intersecting the perpendicular plane of the respective seamed flange at angles of less than 90.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a plan view of a corner junction of a yieldable wall assembly of the character described embodying the present invention and showing in dot-dash lines the positions of the weld seams after shrinkage;

FIG. 1A and 1B are plan views of this junction in the preshrinkage and postshrinkage stages;

FIG. 2 is a perspective view, drawn to an enlarged scale illustrating the junction of FIG. 1;

FIG. 3 is a view similar to FIG. 1 illustrating the junction with petal-shaped gussets; and

FIG. 4 is an enlarged cross-sectional view taken along the line IVIV of FIG. 1A.

In FIG. 4, I have shown the basic elements of a yieldable wall assembly for tankships and the like adapted to carry low-temperature fluid such as methane.

The yieldable wall structure is composed of a plura y of late a y and l g tudina ly on ig ous Sheetmetal plates 1a and 1b (all designated at 1 and 101 in FIGS. 1, 1A, 1B and 3, respectively), the plates being mounted by insulating bolt assemblies on the rigid wall 10 of the ship hold; layers 11, 12 and 13 of load-supporting thermal insulation are interposed between the plates 1a and 1b and the hull 10.

The plates 1a and 1b has upwardly extending peripheral flanges 2a and 2b which are welded together about the periphery of each plate so as to impart a tray-like configuration to the latter. These flanges 2a and 2b have lips 2a and 2b which are turned generally toward one another (parallel to the plane of the plates 1a and 1b) and are welded together along seams 2'. The flanges 2a and 2b diverge somewhat outwardly and thus converge in the direction of a respective perpendicular plane P extending along the weld seam 2 perpendicularly to the plane of the plates 1a and 1b. The seam illustrated on FIG. 4 (in which the perpendicular plane P is shown to be vertical and orthogonal to the plane of the drawing) is designated at 2 and corresponds to the seam formed along each of the edges of the rectangular plates 1a and 1b. The seam is of triangular section and has an upper edge formed at 2' by the actual weld junction.

Upon shrinkage of the plates 1a and 1b (arrow 1a and 1b), the flanges 2a and 2b are flattened somewhat. According to the principles of the present invention, each of the weld scams 2 between each pair of laterally and longitudinally contiguous plates is provided at its opposite ends with a pair of gussets 15 or 15' (FIGS. 18 and 4) which are geometrically similar to one another and are of triangular prismatic configuration.

Referring now to FIG. 1, 1A, 1B and 2, it will be seen that each of the generally prismatic (triangular prism) gussets 15 or 15' of the flanged seams 2, provided with a weld seam 2' as indicated earlier, is formed by an outer fold 4 and an inner fold 5, and a seam portion 16 (FIG. 1A) of the weld seam 2' is bent out of the plane P (extending perpendicular to the plane of the drawing) and then joins at apex 17 the inwardly extending portion 18 of the seam. The corresponding portions 18 and 18' of the gussets 15 and 15' are aligned with one another and welded at the corner 19 so that they extend at an angle of substantially 45 to the orthogonal perpendicular planes P and P mentioned earlier. The portions 16 and 18 are referred to generally in FIGS. 1 and 2 as the upper edges 3 of the joined inwardly and outwardly bent folds. From FIG. 2 it will be seen that the inner and outer folds are welded together at their upper edges 3 while the flanges are further welded along their flanks as represented at 3 in FIG. 2. In FIGS. 1 and 2, the broken line represents hidden portions of the system while dot-dash lines show the system in its normal position and in the position assumed after shrinkage as a result of the filling of the tank with methane or other low-temperature liquefied gases. FIG. 1A shows the corner junction in its unshmnk position while FIG. 1B shows the stretched condition of the gussets.

In the systems of FIGS, 1, 1A, 1B and '2, the distension of the gussets applies stress to the corner 17 whereby a strain in this region is observed. This can be avoided with the system of FIG. 3 in which the plates 101 have flanged seams 102 with welded upper edges 102' as previously described but formed with gussets having outer and inner folds 104 and 105, respectively, such that at the upper seamed edges 103 of these arcuate or round gussets, as shown in 103, the gussets are welded together. In FIG. 3 as well, hidden lines are shown broken while the dot-dash position represents the condition after shrinkage. The gusset arrangement is a petal configuration and is characterized by the lack of angular junctions at which stress may develop.

I claim:

1. A yieldable wall assembly for containers used in transportation of low-temperature fluids comprising a plurality of plates each having upwardly turned peripheral edges, said plates being arranged in continuous side-by-side and end-to-end relationship in a checkerboard array with each four adjacent plates meeting at a common corner with the distal edges of the upwardly turned flanges welded together along flange seams, and a corner-junction structure wherein portions of said flanges of said plates adjacent said common corner are alternately displaced in a direction parallel to the plane of the wall assembly so that the displaced flange portion of each plate is welded together with the displaced flange port on of a contiguous plate, the seams of the displaced flange portions being offset from the respective flange seams beyond the displaced portions.

2. The structure defined in claim 1 wherein the flanges of said plates define external angles of less than 90 with said plane of the wall assembly.

3. The structure defined in claim 1 where n said upwardly bent flanges of said plates adjacent to said common corner are generally arcuately displaced and the seams thereof extend along respective arcs.

4. The structure defined in claim 1 wherein the flanges of each of the four pairs of contiguous plates at said common corner are alternately folded displaced to define an expansion bend, all said expansion bends be ng geometrically similar, each of said seams having geometrically similar bends at the opposite ends thereof with the bends at the opposite ends of each seam being disposed reciprocally on opposite sides of the weld-seam plane perpendicular to the plane of the wall assembly, all of the UNITED STATES PATENTS 1,799,234 4/1931 Huff 220--63 3,114,470 12/1963 McDill 220-10 3,184,094 5/1965 French etal. 3,215,301 11/1965 Armstrong. 3,302,358 2/1967 Jackson.

FOREIGN PATENTS 1,370,087 7/1964 France. 1,171,684 6/1964 Germany. 1,073,713 6/1967 Great Britain.

JOSEPH R. LECLAIR, Primary Examiner I R. GARRETT, Assistant Examiner US. Cl. X.R. 2209 

